BMW Radiator Expansion Tank Cap Coolant Reservoir Cap For 2006 To 2025 1 Series 3 Series 5 Series X Models Replacement Keep Your Engine Cool Prevent Leaks And Maintain Proper Pressure In The Cooling System

BMW Radiator Expansion Tank Cap, Single Replacement
✔️ Direct, OEM-like fit for many BMWs; includes correct pressure sealing

This radiator expansion tank cap is a sealing cap for the coolant reservoir, designed to regulate system pressure and prevent leaks in BMW cooling systems. It’s a common direct replacement for a wide range of models from 2006 to 2025, including 1 Series, 3 Series, 5 Series and X models.

✅ Direct replacement part numbers: 17117639020, 17-11-7-639-020, 17117521071, 17-11-7-521-071
✅ Fits numerous BMW models from 2006-2025 across 1, 3, 5, X lines
✅ Black aftermarket cap for durable, leak-resistant performance
✅ Snap-on installation, no tools required for quick replacement

💡 What is a radiator expansion tank cap and why should I replace it in my BMW cooling system?

- radiator cap maintains system pressure and prevents coolant leaks - replacement helps prevent overheating and air ingress in the cooling circuit - ensures reliable sealing to protect components like the water pump and hoses